Adjustable tuning fork



Feb. 4, 1930.

A. F. CONNERY ET AL I 06 ADJUSTABLE TUNING FORK Filed 001;. 29, 1927 ALDER F CONNERY FREDERICK G. HALLDEN awuewcozs Patented Feb. 4, 1930 UNITED STATES PATENT OFFICE ALDEB F. CONNERY, OF BROOKLYN, AND FREDERICK G. HALLDEN, 0F JAMAICA, NEW

YORK, ASSIGNORS TO POSTAL TELEGRAPH-CABLE COMPANY, OF NEW YORK, N. Y.

A CORPORATION OF CONNECTICUT ADJUSTABLE TUNING FORK Application filed October 29, 1927. Serial No. 229,591.

Our invention relates to electromechanical vibrators and pertains particularly to means for quickly and accurately altering the rate of vibration of devices of this character without interfering with or arresting their vibratory action.

It is well known with vibratory devices of the type employing a tuning fork or reed as a vibrating member to vary ihB PGIIOd of vibration by changing the effective length or the distribution of the vibrating masses. One device for accomplishing this purpose which has been used heretofore consists of a slidable block or carriage adjustable lengthwise of the fork and connected to weights by either pivoted or flexible links, the weights being carried by the tines of the fork. This construction requires a rather elaborate movable carriage and rails or slots for guiding the same and is therefore complicated and expensive to manufacture.

The object of our invention is to provide an inexpensive, rugged and reliable means for mechanically making small changes in the period or rate of vibration of a tuning fork. In our novel device the carriage is entirely eliminated and the adjustment of the period of vibration is accomplished in a direct and thoroughly effective manner by means which impart uniform, simultanenous motion to both of the weights.

The above and other desirable features of our invention is fully set forth in the following description and claims and will be readily understood by reference to the accompanying drawings in which like reference numerals designate corresponding parts throughout and in which:

Fig. 1 illustrates a plan view of our complete device with a portion of the tines of the fork broken away.

Fig. 2 illustrates a side elevation of the same with parts broken away to more clearly show essential features.

Fig. 3 illustrates a section of the same taken on the line 33 of Fig. 2.

The tines of the tuning fork obviously ma be struck mechanically to set the fork in v1- bration and the vibration may be maintained bymeans of an electromagnet acting upon each tine in a manner thoroughly well known In the art. Since it is old in the art to employ electromagnetic means for maintaining a tuning fork in vibration, and since it forms no part of our invention it is deemed unnecessary to describe such means or show it in the drawing.

Referring now to the drawing, the tuning fork 2 is mounted on a base 1 which may be constructed of suitable material and of such dimensions as to form a rigid support. The tuning fork 2 is secured to a raised support provided in the base 1 by means of the nut 7. The slidable weights 3 and 4 are adapted to slide longitudinally with respect to the tines of the fork, and are prevented from rattling or vibrating against the tines by means of springs 5 and 6. The weights are preferably formed of two parts held together by screws as indicated. Racks 10 and 11 are rigidly fastened at one extremity thereof to each of the weights 3 and 4. respectively by means of screws as indicated. The racks pass through guide slots in the journal block 20 as shown in Fig. 3 and are prevented from rattling therein by tension exerted by the leaf springs 12 and 13 supported by plates 17 and 18 respectively. The pinion 16 is carried in the journal block 20 and is adapted to engage both of the racks 10 and 11. A knurled adjusting knob 14 is secured to the pinion 16 by means of which the pinion may be rotated to cause horizontal motion of both racks 10 and 11 and the weights 3 and 41 secured thereto.

Obviously the position of the weights with respect to the longitudinal dimensions of the tines of the fork may by rotation of the knurled knob 14 be accurately determined. For efiicient operation of our device it is advisable to have the pinion 16 and racks 10 and 11 engaged loosely and also to place the block 20 at a position relative to the fork where there will be the least amount of relative motion between the pinion and the racks. The journal block 20 is supported by the angle plate 15 which is attached to the base 1 by means of the nut 7 bolt 8 and locknut 9. It will be observed that the entire organization for providing the mechanical adjustment of the weights is simple, rugged and that it fur-' ther may be attached to any fork in an extremely simple manner.

It will be observed from the foregoing that when it is desired to alter the period of vibration of the fork it may be readily and easily accomplished by merely rotating knob let which will impart longitudinal motion to the weights 3 and 4, as already explained, without interfering with the vibratory action of the fork. Further it will be noted that as both weights are. moved through equal distances simultaneously, since they are both positively controlled by pinion 16, the distribution of mass along each tine will be equal, thus maintaining the eflicient action of the fork.

Having thus completely described our invention, we claim:

1. An adjustable tuning fork comprising, a base, a tuning fork carried on said base, a weight carried by each tine of said fork and adapted to be moved longitudinally thereof, means attached to each of said weights and lying adjacent to said tines whereby longitudinal motion is imparted to said weights, and rotary means common to both of said last mentioned means for imparting longitudinal motion thereto.

2. An adjustable tuning fork comprising, a base, a tuning fork carried on said base, a Weight carried by each tine of said fork and adapted to be moved longitudinally thereof, a rack attached to each of said weights, said rack lying adjacent to said tines, a pinion common to both of said racks and means for rotating said pinion.

3. The combination with a tuning fork of a weight slidably mounted upon each tine, a rack attached to each of said weights, said rack lying adjacent to said tines, a journal, a pinion carried by said journal and adapted to engage both of said racks and means for rotating said pinion in said journal.

4. In combination with a tuning fork a base provided with a standard to which said fork is secured, a weight slidably mounted upon each tine, a rack attached to each of said weights, a journal supported by said standard, a pinion carried by said journal, said pinion being common to and engaging both of said racks, and means for rotating said pinion to move through the medium of said racks, said weights simultaneously longitudinally on said tines.

5. A tuning fork comprising, a base, a standard mounted on said base, a pair of tines carried on said standard and an attachment for said fork comprising, weights adapted to be slidably mounted on said tines, a rack attached to each of said weights, a journal supported by said standard, a pinion carried by said journal and adapted to engage both of said racks and means for rotating said pinion in said journal.

6. In combination, a reed adapted to vibrate, a Weight slidably mounted on said reed, a coupling member mechanically independent of the vibrating portion of said reed and extending approximately parallel thereto, connecting said weight to a point on the reed longitudinally adjacent the axis of vibration of said reed.

7. In combination, a reed adapted to vibrate, a weight slidably mounted on said reed, a coupling member mechanically independent of the vibrating portion of said reed and extending approximately parallel thereto, connecting said weight to a point on the reed longitudinally adjacent the axis of vibration of said reed and means for varying the length of said member.

ALDER F. CONNERY. FREDERICK G. HALLDEN.

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